"Crosby should write an introspective book: Why People Won't Talk to Me Anymore," Young said. "He made a lot of great music for a long time. I don't know what happened with David. I got nothing to say. I love Stephen [Stills]. I love Graham Nash. ... If a reunion happens, it would be a surprise. I won't close the door on anything. I can hold a grudge with the best of them but only if there's a reason for it."

Crosby himself, touted his new doc as being "honest enough to qualify as an apology." He acknowledged his predilection to being "contentious" as one of the reason he's struggled to maintain friendships with his CSNY mates.

"We were also very s----y to each other over and over and over again, unkind and disloyal," Crosby noted.

There would be other stumbling blocks for a CSNY reunion. Young himself has been reluctant to do much touring at all over the past year, having recently canceled plans to support his latest album, Colorado, with live shows.

He clarified to AARP that thanks in no small part to his "health-oriented" wife, Daryl Hannah, he recently lost over 30 pounds. So it's not his health keeping him from touring, he says, it's his busy studio schedule.

Nash has expressed little interest a CSNY reprise, noting in one interview with Q104.3 New York in 2017 that the former band mates weren't talking and needed a "break" from one another.